Ulcerative colitis is an inflammatory bowel disease of unknown etiology. Many studies have shown that serum markers called antineutrophil cytoplasmic antibodies with perinuclear staining (pANCA) are present in 68-85% of patients with ulcerative colitis. Recently, specific histone H1 peptides have been identified to develop and optimize an ELISA based assay using these histone H1 peptides to detect pANCA marker antibodies. Therefore, the peptide ELISA test will become a second-generation serological diagnostic test for ulcerative colitis (UC). The peptides will be used as the solid phase binding component in place of freshly prepared human neutrophils that are the basis of the current commercial assay. Compared to the test that makes use of neutrophils, the peptide ELISA will be produced more consistently, offer considerably greater shelf stability, and lead to a lower test cost. This improvement will extend the pANCA test capability to other test formats, such as automated clinical chemistry analyzers. PROPOSED COMMERCIAL APPLICATION: Serology tests for pANCA markers are currently in commercial use as an important non-invasive method to diagnose ulcerative colitis. The user of specific histone H1 peptides in these tests will allow expansion of the technology base from ELISA to technologies such as immunochromatography, magnetic particle separation assays, and rapid clinical analyzers, thereby making these serum assays widely available for inflammatory bowel disease diagnosis.